Electronic detector for use with impulse regenerators



Dec. 10, 1963 H. FAULKNER ELECTRONIC DETECTOR FOR USE WITH IMPULSEREGENERATORS Filed Dec. 12, 1958 BREE mbw q mmm Sm X095 1 Ii. 5 mumbomag/w IN V EN TOR. ALFRED H. FAULKNER ATTY.

3,114,951 ELECTRGNHI DETEQTUR FUR 5313 WITH DTPULSE REGENERATQRd AlfredH. Faulkner, Redondo Beach, Calif., assignor to Automatic ElectricLaboratories, End, a corporation of Delaware Filed Dec. 12,1ass,s@i.N0.7se,i2s 1 Claim. ct. sin-see This invention relates ingeneral to impulse regenerators and in particular to impulseregenerators of the type utilizing electronic means for detecting thestored digital information.

in the telephone art it is often necessary to correct dial pulses as totheir amplitude, wave shape, or both. Pulse repeaters are generally usedto accomplish this purpose, and, since a new pulse is transmitted aseach dial pulse is received, it is unnecessary to have digit storagefacilities.

An impulse re erierator however, not only corrects for pulse wave formand amplitude distortion but also compensates for frequency deviation ofthe incoming pulse train. Assuming that a frequency of 10 p.p.s. isdesirable for existing switching facilities and that incoming dial pulsefrequency may range between 8 p.p.s. and 12 p.p.s., it is at onceapparent that a new pulse cannot be generated upon reception of each ofthe old pulses if the desired 10 p.p.s. frequency is to be attained.Therefore, it is necessary to provide some means for storing theincoming impulses before beginning transmission of outgoing impulses.

Impulse regenerators of the prior art utilized a variety of elements asstorage devices. Among these were relays and rotary switches.(,apacitors were also employed, but since sensitive detecting means werenot used, the storage system generally proved expensive and bulky.Applicants electronic detecting circuit makes it feasible to use smallinexpensive components, such as small capacitors and magnetic cores, asstorage elements in impulse regenerators.

Accordingly, it is an object of this invention to provide an impulseregenerator, compatible with existing telephone switching facilities,which utilizes small inexpensive components such as, electrolyticcapacitors and magnetic cores, as storage elements.

Another object is to provide a novel electronic type detecting circuitfor detecting the potential on marked ones of a group of small storagecapacitors.

A feature of this invention is the provision of a novel detectingcircuit in an impulse regenerator for controlling transmission ofregenerated pulses and also for timing output interdigital pauseperiods.

Another feature of this invention is the use of an electronic pulseamplifying circuit in an impulse regenerator which permits the use of acommon, low powered, electronic source of accurately timed voltagepulses for controlling the regenerator output pulse frequency.

Other objects and features of the invention will be apparent from areading of the specification taken in conjunction with the drawings inwhich:

FIG. 1 is a schematic representation of an impulse regenerator utilizingsmall electrolytic capacitors as storage elements.

Referring now to FIG. 1 of the drawings, a brief description of theoperation of this impulse regenerator, which uses capacitor storage,will be given. The regenerator is seized and held in a conventionalmanner. As digital impulses are received from the preceding equipment,the wiper of a rotary switch 452 is stepped, in synchronism with thereceived impulses, across a series of individual storage capacitorsC1C33. During each interdigital pause between impulse series a markingcircuit is completed through the rotary switch wiper to the StatesPatent "ice capacitor then in contact with the wiper. The charging ofthe capacitor indicates the digit registration. Succeeding digits arestored in a similar manner.

At the time of seizure, operating potentials are applied to atransistorized detecting circuit 1% and to a transistorized pulseamplifying circuit 49. Detecting circult 1% is connected at this timefor monostable operation. The base electrode of one of the detectingcircuit transisters is connected to the switch wiper of another rotaryswitch 43, the bank contacts of which are also connected to theindividual storage capacitors. The normally oli transistor 89 of themonostable combination is rendered conductive due to a base potentialapplied from battery over the wipers and first bank contacts of both ofthe switches. Upon receipt of the first digital impulse this basepotential is removed and the detecting circuit assumes its stablecondition. When this condition has con reached, a circuit, which will becompleted during the first interdigital pause period, is prepared forrenderin? the monostable detecting circuit 1-90 bistable, and foroperating the pulse amplifier 49.

A common pulse generator or source of clock pulses 47 is connectedthrough a diiierentiating capacitor to the base of the normally of?transistor 59 of the pulse amplifier, which transistor has an outputpulsing relay 70 connected in its collector circuit. The diiferentiatingcapacitor acts to convert the square wave voltage output from the commonpulse generator into a series of positive and negative voltage pips. Thepositive voltage pips generate small pulses of collector current in theoff transistor, but these pulses are insufiicient to operate the pulsingrelay.

During the interdigital pause after the receipt of the first digit, anaforementioned circuit is completed which renders the detecting circuitbistable, and connects a ground potential to the base of the ontransistor 61 in the pulse amplifier 49. Now, thenext positive voltagepip to the base of the o' transistor of the pulse amplifier switches theon transistor oil and locks the previously ofi transistor on. Thecollector current is now suificient to operate the pulsing relay 70. Thepulsing relay, in addition to transmitting output pulses, also causesthe motor magnet 45 of the second switch 43 to operate. Upon restorationof the pulsing relay, the motor magnet restores and steps the switchwiper to the next contact. This process is repeated until the switchwiper of the second switch 43 rests on its bank contact associated withthe marked capacitor. The charge on the marked capacitor is impressed onthe base of the non-conducting transistor 3% of the detecting circuit160, which, it will be remembered, is now bistable and causes thistransistor to be switched on. The change in state of the detectingcircuit causes it to revert to monostable operation. The pulse amplifier49, in response to the detecting circuit, also reverses terminating theoperation of the output pulsing relay and the stepping of the secondswitch.

When the detecting circuit 1% is switched by the application of thecharge of the marked capacitor to the base of its non-conductingtransistor 59, an erasing circuit is closed which neutralizes the chargeon the marked capacitor. The now monostable detecting circuit is in anunstable state and will remain so if another digit has not beenreceived. If another digit has been stored or is in the process of beingstored, then the base battery potential necessary to hold the detectingcircuit in its unstable state will not be present and it will assume itsstable condition. Usually a second digit will either have been stored orbe in the process of being stored and the time required for thedetecting circuit to switch from its unstable to its stable conditionwill determine the pause period between the output impulse series. Whenthe detecting circuit reaches 3 its stable state, it is againimmediately converted for bistable operation md the above processes arerepeated.

A detailed explanation of the operation of the circuit of FIG. 1 willnow be given. The regenerator is marked idle to other switches bybattery impressed on lead 5 via cit-normal spring contacts 53 and 33.The switch is seized in a well known manner and a loop circuit is closedto operate relay it Relay in operating closes, at contact 11, anoperating path for relay 15. Relay in operating prepares, at contact 17,operating paths for relay 25, motor magnet 41'? and relay 35. t contactits battery potential is connected to the detecting circuit lit-ii,comprising transistors 8t) and 35, and at contact 21 ground potential isconnected to the pulse amplifier circuit 49, comprising transistors 5and 64 At contact 23 ground is connected to lead 5 to mark theregenerator busy to other switches.

For the sake of clarity the process of storing an incoming digit will bediscussed before analyzing the effects of the aforementioned potentialson the detecting and pulse amplifying circuits. Assume that the digit 2is dialed by the subscriber. On the return of the dial, contact 1 of thesubscribers subset opens (for the first time) and relay 10 restores.Relay lit? in restoring completes, at contact 12, obvious operatingpaths for relay 25 and motor magnet 4%. Rotary switch 42 is the typethat steps upon estoration of its motor magnet and consequently nostepping occurs at this time. Relay 25 in operating removes, at itscontact 2?, battery potential from the switch wiper of switch 42 andprepares, at its contact 28, to place ground potential thereon. Atcontact 29, an operating path is prepared for relay 35.

As the dial of the subscribers telephone continues moving toward itsnormal position, contact ll recloses and relay 1% is reoperated. Theoperating path to relay 15 is again completed, helping to maintain thisrelay, which is slow-to-release, operated during the open periods ofcontact 1. At contact 12 the operating path to motor magnet 40 isbroken. Motor magnet 4%, in restoring, causes the switch wiper of switch42 to step to the next bank contact and, due to the reclosure of itsinterrupter spring contact 41, an operating path to relay 35 iscompleted. This path is as follows: battery, relay 35, contact 29 ofrelay 25, which also remains operated during the open period of contact1 due to its slow-to-release feature, interrupter spring contact 41,contact 19, contact 11, and ground. Relay 35 looks to ground via contact21, its contact 37, and contact 29. At contact 36 a ground circuit iscompleted to the wiper of switch 42. When switch 42 was stepped, itsolt-normal spring contacts 32 and 33 restored, but these operations haveno significance at this time.

The storage elements in this regenerator are small individualelectrolytic capacitors, C1 to C33 connected between ground and theparalleled bank contacts of switches 4-2 and 43. For the purposes ofclarity, only a few of these capacitors are shown. The ground which hasbeen connected to the wiper of switch .2 is now effective to neutralizeany charge present on capacitor C2.

The subscrihers dial opens the line loop at contact 1 for the secondtime and relay 10 restores. Motor magnet 40 reoperates, and itsinterrupter spring contact 41 opens the original operating path to relay35, but this relay remains operated over the holding path previouslydescribed. Relay 25 is energized again to help keep it operated duringthe open periods of contact l. Contact i now closes and remains closedduring the interdigital pause period and relay ll reoperates. Motormagnet 49 is deenergized and the wiper of switch 42 steps to its thirdbank contact. After a brief delay relay 25 restores, and at contact 29restores relay 35. Relay 35 in restoring further opens, at its contacts36, the open ground circuit to the switch wiper of switch 42. This relayis incorporated in the circuit to guard against the accidental dischargeof a marked capacitor when a subsequent digit is received. Relay 25 inrestoring also reconnects, at its contact 27, resistance battery to theswitch wiper or switch 42 which is now connected to 4 capacitor C3.Capacitor C3 charges over this path which consists of battery,resistance 26, contact 27, the switch wiper of switch 42, capacitor C3,and ground. Relay 25 also connects ground at its contact 39 to relay 9%)which, as will be shown presently, will complete an operating path torelay 9%.

Returning now to a time just prior to seizure of the regenerator, itwill be noted that transistor of detecting circuit 1% is conductivealong its emitter-base path. This path is as follows: ground, resistance31, emitter 77 and base 78 of transistor 80, diode 74, the switch wiperof switch 43 which is resting on its first bank contact, the junctionwire interconnecting the first bank contacts of switches 42 and d3, theswitch wiper of switch 42, contact 27, resistance 26, and negativebattery.

Upon seizure, closure of contact 16 renders transistor 8%) conductivealong its emitter-collector path as follows: ground, resistance 8i,emitter 77 of transistor 89, collector T E", resistance 88, contact 16,and resistance battery. Emitter 77 of transistor 3% is connected toemitter S2 of transistor 85, hence there can be no potential differencebetw on them. As transistor 80 conducts along its emittercollector path,its emitter 77 is rendered less positive due to the potential drop inresistance 81. Consequently, emitter 82 of transistor 85 is renderedless positive and this transistor is prevented from conducting. It willbe noted that these transistors are connected for monostable operationsince capacitor 89 is connected between base 78 of transistor 36 andcollector 84 of transistor 85. However, the arrangement is maintained inan unstable state due to negative battery applied to base 78 oftransistor 80 through diode 74.

When relay 25 operates upon receipt of the first incoming digitalimpulse, it removes this negative potential from the switch wiper ofswitch 42 and hence from base 7 8 of transistor 3%. As a result theemitter base current of transistor is diverted through resistor 76,capacitor 3%, relay 96, contact 16, to negative battery. Capacitor S9begins to change and drives base 78 more and more positive which resultsin transistor St) being driven to cut-oil. As transistor Bil is driventowards its non-conductive state, its emitter potential is raised,allowing transistor 85 to conduct. The emitter-collector current path oftnansis-tor S5 is as follows: ground, resistance 81, emitter 82 oftnansistor 85, collector 3 relay 96, contact 16, and resistance battery.Over this path trelay 96 operates.

Relay 96 in opens-ting completes a shunting ground path at contact 5 8to capacitor Cl, thereby discharging this capacitor. At contact anoperating path for relay fi is prepared, which path is still incompleteat contact 39. When relay 2.5 restores during the first interdigitalpause, this operating path is completed and relay 9% operates and locks.Relay gt? in operating shorts out, at contact 92, capacitor 89 andconverts detecting circuit 100 from monostalble to bistable ope-ration.Since detecting circuit Elli is now bistable, transistor 80 maybeswitched on (thus switching transistor 35 off) by application ofnegative potential to its base 73.

The pulse amplifying circuit d9 comprises a pair of tnansistons 5t) and6% connected as a :multivi-hrator. A source of timed voltage pulses 47,which may be a pulse generator, preferably an electronic one employingtransistors, is connected through a small capacitor 51 to base 56 of"transistor 5 Capacitor 51 differentiates the rectangular out-put waveform of pulse generator 47 to impress a series of alternatnig voltagepips on the base of tnansistor Returning again to seizure, ground isconnected via contact 23. to pulse amplifying circuit 49, and since theground to base 62 of transistor as is open at con-tact 95, transistor 6%conducts. When transistor 68 conducts along its e-mieter-collector path,its collector 63 swings positive and prevents transistor 5% fromconducting. The voltage pips applied to the base of transistor 5G giverise to corresponding brief pulses of collector current in thistransistor, but

5 these brief pulses of current are insufiicient to operate outputpulsing relay 7! which is connected in its collector circuit.

As mentioned previously, relay 2'5 restores during the interdigitalpause period, completing an operating path for relay 9'9 and relay 93operates and locks. To repeat, rela 9i? in operating shorts outcapacitor 89, thus convetting the monostabie detecting circuit 104 forbistable operation. Under these conditions negative voltage applied tothe base of transistor 80 will cause the circuit to switch.

Relay "90 in opera-ting also opens, at its contact 93, the groundc':cuit to the wiper of switch '43 to preclude the possibility ofdischarging a marked capacitor. At contact 95 ground is connected viaresistor 64 to base 62 of transistor 69.

It will be remembered that voltage pips are continuously applied to base5'6 of transistor 50. The spacing of these pips determines the impulseratio of the outgoing impulses from the regenerator. It will also berecalled that with relay l unoperated, the brief pulses of collectorcurrent in transistor 5% were insufiicient to operate relay 7%. However,with relay 9% operated, the brief pulse of collector current intransistor 50 during a positive voltage pip is effective to cut oiltransistor 68, causing its collector 63 to swing negative and switchtransistor 50 on in the usual manner. When transistor 59 locks in itsconductive state, relay 7 operates. Relay 70 in operating opens, atcontact 72, the outgoing pulse loop, and at contact 71 completes anoperating circuit to motor magnet 45.

Transistor 55 remains conductive until a subsequent negative voltage pipdrives it to cut off, causing the circuit to revert to its previousstate, that is, with transistor '68 conducting. Relay 7 0 restores,re-closed the outpulsing loop at contact 72, and breaks the circuit tomotor magnet 45. Upon the restoration of motor magnet 45 the switchwiper 43 is stepped to its next bank con-tact. Succeeding positive andnegative voltage pips applied to the base of transistor cause relay 7%to operate and res-tore as previously described and the switch wiper ofswitch 43 is stepped upon each restoration of relay '70.

Since the first received digit was assumed to bea 2 capacitor C3 was neatively charged. After relay 7%) has transmitted two outgoing impulsesto the line, the switch wiper of switch 43 engages the bank contact towhich capacitor C3 is connected. The negative voltage on capacitor C3 isimpressed on base 73 of transistor 8 0 via the switch wiper of switch 43and diode 74. This negative potential causes the detecting circuit b toswitch, rendering transistor 8i: conductive and transistor 85non-conductive. When transistor 85 becomes nonconductive, relay 96restores and at its contact 99 restores relay 9t Relay 9:; in restoringremoves, at contact 9:, the ground to base 6 2 of transistor 6%Succeeding voltage pips applied to the base of transistor 5% are againineffective to operate relay 7i and the transmission of outgoingimpulses is terminated.

At this time another digit will ordinarily be stored or be in theprocess of being stored and the switch wiper of switch 42 will not beresting on its bank contact associated with capacitor C3. Therefore, thedetecting circuit lu in absence of the holding battery on base 78 oftrans stor 8%, will revert to its stable condition, ie. with transistor85 conducting. The time required for this switch ng action to occur willbe determined by the charging time of capacitor 89. This capacitorcharges through resistors 75 and 76 which are connected in parallelwithvariable resistance 97. Variable resistance 97 is utilized to permitadjustment of the RC time constant and hence the outgoing interdigitalpause period.

if smother digit has not as yet been received, the switch wiper ofswitch 42 would be resting on the bank contact connected to capacitorC3. Relay 25 would be restored and battery would be impressed viaresistance 26, contact 27, the switch wiper of switch 42, the junctionwire between the third bank contacts of switches 42 and 46, the switchwiper of switch 43, and diode 74 to the base 7 8 of transistor 86, thusholding this transistor conductive pendiug receipt of another digit. Ifanother digit has been stored or is in the process of being stored,relay '90 would reoperate during the next incoming interdigital pauseperiod and transmission of output pulses would take place as previouslydescribed.

The above procedure is repeated for the remaining incoming digits. Whenthe impulse regenerator has transmitted t he corresponding series ofoutput impulses, switch through or some other appropriate switchingaction occurs, breaking the bold path for relay l0. Relay 15, after thepassage of its slow-to-release time, restores. The regenerator is notmarked idle to other switches since resistance battery is prevented fromappearing on control lead 5 due to open off-normal springs 33 and 53.Relay 15 in restoring closes, at contact 18, an operating path to motormagnet All. This path is as follows: ground, contact 12, contact 18,restored oil-normal spring contact 32, motor magnet interrupter springcontact 41, contact 20, motor magnet 49, and negative battery. Since theinterrupter spring contact 41 is now serially connected in the operatingpath of motor magnet 46, motor magnet 4i? operates self-interruptedlyand stops the switch wiper of switch 42. around to its normal position.When switch 42 is at normal, its oil-normal spring contact 32 operatesand prevents any further stepping.

A similar circuit exists for motor magnet 45. This path is as follows:ground, contact 22, restored off-normal spring contact 44, motor magnetinterrupter spring contact 46, motor magnet 45, and battery. Over thispath motor magnet 45 operates in a self-interrupted manner and steps theswitch wiper of switch it to its normal posit-ion. When switch 4 3 is atnormal, its oil-normal spring contact 44 operates breaking the circuitto motor magnet 45 and prevents any further stepping. When both switch42 and 43 have been returned to normal, off-normal springs 33 and 58 areoperated and permit resistance battery to be impressed upon lead 5,thereby marking this regenerate-r idle to other equipment.

It will be noted that relays 25 and 35 are held operated during thereturn stepping of switch 42. Thus, a solid ground is kept on the switchwiper resulting in the neutralization of any charge on the storagecapacitors.

All of the transistors shown in the above circuits are of the PNP typebut NPN types can readily be employed by one skilled in the art.

While the invention has been described with a certain degree ofparticularity, it is apparent that numerous. modifications may be madewithout departing from. the true spirit and scope of the invention asdefined in the claim.

What is claimed is:

In combination a bistable flip-flop circuit including a first and secondtransistor each having a base electrode, an emitter electrode and acollector electrode, the second transistor being normally conductive,means for applying a potential to the base electrode of the firsttransistor to render the first transistor conductive and render the second transistor nonconductive, means to render the first transistornon-conductive and render the second transistor conductive inmemos-table fashion compn'sing: a capacitor r connected to the baseelectrode of the first transistor; relay means connected to thecollector electrode of the second transistor rendered inoperative inresponse to the rendering of the first transistor conductive to remove ashunt path to charge the capacitor to a predetermined potential; thesecond transistor rendered conductive and the first transistor renderednoncond-uctive in response to the capacitor being charged to thepredetermined potential, the relay means rendered operative in responseto the first transistor being rendered n-ouconductive, and the capacitordischarged in response to the why means being rendered 0pera'tive.

References Cited in the file of this patent UNITED STATES PATENTSFleming-Williams Feb. 13, 1951 Trent J-an. 12, 1954 Schneider Mar. 18,1958 Stuart-Williams Nov. 25, 1953 Geiskr has 2, 1959 Bird June 9, SmymhJune 16, F-ankave July 14, Moody July 21, Lawrence Aug. 25, Fwlkner May31, Maybe-Pry Aug. 8, Beeler Nov. 7, Schubert Nov. 21,

